13th International Conference on Fracture June 16–21, 2013, Beijing, China Table 5. Comparison of measured data with data from the literature Grade/Mark Ry Rm ΔKth n ΔKfc N/mm2 N/mm2 MPam1/2 MPam1/2 and mm/cycle MPam1/2 37C 270 405 7,69 3,60 62,70 St38b-2 280 440 5,5 3,7 45 DP-25156 350-380 790-820 – 2,20 261,01 E420C 450 595 5,72 2,55 100,41 H60-3 500 630 5,9 3,8 50 TRIP-28670 ≥500 560-720 – 2,06 320,73 X80TM 540 625 – 2,49 136,57 H75-3 600-680 – 4,3-5,2 2,5-2,7 70-75 QStE690TM 780 850 – 2,39 – N-A-XTRA 70 810 850 2,7 2,7 88 S960QL 1007 1045 – 2,44 125,11 XABO 1100 1125 1339 – 2,00 116,41 5. Conclusions Based on the results of our experimental tests, evaluated samples and data can be found in the literature the following conclusions can be drawn. − The proposed method can be generally applied for determination of fatigue crack propagation limit curves for steels and high strength steels, and their welded joints under mode I (tension) and mixed mode I + II (tension and shear) loading conditions. Additional information of applications of the proposed method for metallic materials (e.g. pressure vessel steels, aluminium alloys, austempered ductile iron) and non-metallic materials (e.g. silicon nitride ceramics, polymers, reinforced polymer matrix composites) see in our earlier works in the literature [10, 21-23]. − The limit curves calculated by both methods represent a compromise of rational risk (not the most disadvantageous case is considered) and striving for safety (uncertainty is known). − Based on the determined fatigue design limit curves integrity assessment calculations can be done for operating structural elements and structures having cracks or crack-like defects: = determination of propagable an critical crack sizes; = calculation of lifetime determined by the propagable crack size; = calculations of remaining lifetime functions, influences on the lifetime values and lifetime function (parameter study); = reliability of remaining lifetime estimation; = calculation of damage parameter and damage function [24]. − The examinations of the welded joints should be continued. The welding technologies, the welding parameters and their influences should be investigated, on the basis of their influences on the properties and the adequacy of the welded joints [25, 26]. Acknowledgements Author wishes to acknowledge the assistance given by the National Scientific Research Foundation (OTKA F4418, OTKA T022020, OTKA T034503 and OTKA T049126), furthermore the Agency for Research Fund Management and Research Exploitation (GVOP-3.1.1.-2004-05-0215/3.0) for supporting the earlier executed research. The research work has continued as a part of the TAMOP-4.2.1.B-10/2/KONV-2010-0001 project, and will be continued as a part of the -8-
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